As a weight for adjusting the balance of a rotating body such as a rotor in a motor of a brushless outer-rotor type or a brush motor and a polygon mirror for use in a laser printer, there have been used adhesives of epoxy resin singly or combined with powder having large specific gravity such as metal powder.
Furthermore, the adhesives obtained by adding glass having large specific gravity such as lead oxide, titanium oxide and barium oxide to the ultraviolet curing resin have been allowed for. These adhesives (weight means) have been used in such a manner that they are filled in a part of the rotating body and hardened in order to adjust the balance of the rotating body.
However, in the case of using the singly composed adhesive as a weight, the quantity of the adhesive to be applied becomes increased because the adhesive alone is as small as about 1 in specific gravity. Thus, there cannot be secured room for accommodating the designated amount of adhesive in a small-sized motor, and consequently, sufficient adjustment of the balance of the rotor in the motor cannot be fulfilled.
The adhesive obtained by adding powder having large specific gravity to epoxy resin has also suffered a disadvantage such that the number of processes for producing the adhesive of two-fluid mixing type is increased because a mixing process is necessary therefor, and there is a possibility that the specific gravity of the adhesive is reduced due to air bubbles being possibly merged into the adhesive in the heating process.
The adhesive of single-fluid type requires a heating process in production, and therefore, is unfavorable for mass-production. When an article to be supplied with the adhesive has plastic component parts, disadvantageously, it must be kept away from heat brought about in the heating process for hardening the adhesive.
In order to eliminate the aforementioned drawbacks, it has been attempted to add lead oxide, titanium oxide, barium oxide or the like to an adhesive resin which is hardened by active-energy rays. However, ultraviolet curing resin alone has been generally used as a weight. Thus, such a resin adhesive is likely to become thinner on hardening and takes much time to be hardened. Moreover, the resin adhesive entailed a disadvantage such that unhardened part of the adhesive applied to an object still remains to unbalance the object, and adjustment of the balance of the object becomes insufficient.